Resignation from the job...

If you resign within 3 months of your current job, surely it will affect on your next job search. Chances of interview invitation reduces and during interview they will ask you and you have to explain why you left your previous company and you explanation will depend whether they consider you or not.
Generally its advised to secure a job offer first then resign, but it depend on the case and reason of resignation.

One early resignation may hurt you. Multiple early resignations will kill your chances as it shows a pattern.

Bob K

Are you on a 3 month trial period. If so then you should be able to resign, but as Bob stated, early resignations are looked upon negatively by future employers. It shows a mindset which shows lack of commitment on your part.

Could it be that using the word 'resignation' reveals the mindset ?

Depends on the situation, of course it may affect the career when the candidate is in early stage. Challenge lies in coping with the work culture and fast pace life style. At the same time the decision taken by candidate should be substantiated with valid reason, to step into another position

Thank you all for your replies. I don't like my job. I couldn't adapt it. I have become more asocial, shy and unhappy.

Also i don't like the city i live in somehow. I would like to work abroad. Those are the reasons.